This invention relates to the reinforcement of a front side door aperture in motor vehicles aimed at reducing body deformations in the event of offset collisions.
Many studies have recently been devoted to the deformation resistance of motor vehicles in so-called offset collisions, particularly from the front. Offset collisions refer to collisions in which only a proportion, in most cases between 40-60%, of the front of the vehicle hits an object, in crash tests normally a concrete barrier or the like, thus only a proportion of the front section of the vehicle can be used as a deformation zone. Such collisions may totally destroy certain front structures, particularly if the front structure has been designed mainly to resist barrier crashes in which the entire front is involved in the deformation. If the offset collision is so minor that only a few per cent of the front of the vehicle hits the object, which means that the beams forming the front section are not involved, or are only involved to a small degree in the deformation work, the crash pulse extends to the wheel of the vehicle, which behaves largely as a non-deformable body during most of the initial phase of the deformation, at least until the deformation assumes such dimensions that the wheel is punctured. The crash pulse deforms the wheel suspension and the wheel is forced backwards towards the rear part of the wheel housing. Passenger cars are often designed so that the part of the wheel housing against which the wheel strikes forms part of the safety cage for the passengers, namely the A-pillar, by which is meant the front roof pillar and its extension down to the sill beam. The B-pillar consists of the pillar located behind the driver and front passenger door respectively.
When the crash pulse is propagated via the wheel to the bottom half of the A-pillar, at its connection to the sill, the door and the door aperture frame begin to be deformed and to absorb the crash forces. What designers try to ensure, in order to comply with stringent standards and safety requirements, is that the door aperture frame and the door are maintained intact as far as possible after the crash so that the doors can be opened, enabling the driver and passenger to leave the vehicle quickly.
One way of reinforcing the door frame is to accommodate the door frame in a stronger, and hence also heavier, structure. This is undesirable because the weight of the vehicle affects its petrol consumption. Another alternative may be to reinforce the door aperture frame in the area of the impact of the wheel, but this solution leads to a situation, in most cases, where the crash pulse is only propagated a small distance into the door aperture frame, with an attendant collapse further in along the sill. Another problem with this is that if the sill beam is made too stiff the wheel may begin to migrate up over the A-pillar during deformation of the front structure, which will begin to subject the A-pillar to buckling which may deform the entire door frame under much lower force stress.